Generally, navigation systems are systems to provide navigation information for driving of vehicles, such as cars, using artificial satellites. The navigation systems are referred to as automatic navigation systems.
The navigation systems receive, by using GPS receivers, Global Positioning System (GPS) information from GPS satellites floating above the earth, and calculate locations of the navigation systems themselves based on the received GPS information. The navigation systems may provide various information helpful for driving of vehicles by notifying users of a current vehicle location based on location information of the navigation systems themselves, calculating moving routes to desired destinations, guiding the users according to the moving routes, and the like.
Specifically, the navigation systems receive the GPS information including latitude information and longitude information from the GPS satellites, and calculate and output location information of vehicles. Also, the navigation systems perform a map matching of the outputted location information with map information such as geographical features, roads, buildings, and the like, being disposing according to latitudes and longitudes, and show moving routes from current locations to destinations which the users desire. The navigation systems perform road guidance showing the moving routes to the destinations by using maps on reduced scales fixed on display apparatuses, and notify the users of moving directions at intersections by using images or voices.
Also, the navigation systems cannot accurately perform the road guidance due to errors between the GPS information and the map information when the map matching is performed by using only the GPS information.
As an example, when vehicles turn left/right, the navigation systems may generate errors between actual locations of the vehicles and locations of the vehicles on the navigation systems when the map matching is performed. As another example, when vehicles actually leave moving routes, especially when the vehicles leave the moving routes from similar-angled links, that is, roads, there is a problem that the navigation systems belatedly detect points in time when the vehicles leave the moving routes. As still another example, when vehicles are driven/stopped in areas where the GPS information cannot be received, for example, tunnels, the navigation systems cannot recognize whether the vehicles is driven/stopped in the areas where the GPS information cannot be received.